It is very common practice in treating a patient that a hypodermic needle may be utilized either to draw blood or to inject a substance into a patient. A danger is involved here if, after puncturing the patient with a needle either for drawing blood or introducing a substance to the patient, the needle continues to be exposed and presents a safety hazard.
Accidental injury with a used hypodermic or phlebotomy needle is not uncommon with health care workers including nurses, physicians, laboratory workers, and housekeeping personnel. Such needle sticks or punctures can result in transmission of hepatitis and potentially the Acquired Immunodeficiency Syndrome, otherwise known as AIDS, and other transmittable diseases.
Accidental needle sticks or punctures can occur when a blood drawer attempts to recap a needle after use or leaves a contaminated needle exposed on a work surface where the blood drawer or other workers may accidentally impale themselves. This problem had previously been recognized and is described in various previous patent publications. For many years it was common practice merely to recap the needle after use with a protective shield.
In view of these known hazards with used hypodermic needles and syringes, various constructions of such syringes have been proposed to cover or occlude the cannula after use. For example, U.S. Pat. No. 4,874,383 discloses a syringe shield which can be drawn out over the needle and firmly locked into position to prevent accidental contact of the user with the needle.
U.S. Pat. No. 4,973,316 discloses a syringe in which the needle is retractable into a hollow barrel after use. The needle is subjected to the energy stored in a compressed spring; when the spring is permitted to expand, it will carry the needle into the tube.
U.S. Pat. No. 4,747,831 discloses a device in which the needle is spring-loaded and may be retracted in a tube or what may be described as a shell member so that after use on one patient it no longer presents the risk of puncture or scratching to the user. U.S. Pat. No. 3,314,428 also discloses a structure in which a needle is retracted within a sheath or tube after use.
Other U.S. patents as disclosed and discussed in the Information Disclosure Statement accompanying this application show other devices for retracting a hypodermic needle or cannula into a protective shell or region after use thereof either for drawing blood or intraveneous injection of fluids in which the needle is used for piercing a patient. These known hypodermic syringes are not easy to assemble, and in some cases, require the use of both hands in order to release the retraction mechanism to withdraw the needle from its position of use.
The present invention provides a new and improved hypodermic needle assembly in which after use the cannula may be withdrawn to an innocuous position where it is not possible to wound the user of the needle.
An object of this invention is to provide a new and improved hypodermic syringe with a retractable needle or cannula.
Another object of this invention is to provide a syringe with a retractable needle which is easily manipulated with one hand.
A further object of this invention is to provide a new and improved syringe with a retractable needle which is of simplified construction.
A still further object of this invention is to provide a retractable hypodermic needle assembly which can be coupled with or be made part of a unit designed to fill an evacuated collection vessel with blood (phlebotomy) or other body fluids. A still further object of this invention is to provide a retractable hypodermic needle assembly with a retraction mechanism which is both rapid and forceful enough to automatically pull the needle out of the puncture wound of the patient and do so virtually instantaneously.